Mackie as he preferred to be called was born in Big Spring, the oldest child and son born to Betty Akins O'Brien and Marvin Jones O'Brien. His father was employed by the Texas and Pacific Railroad and was president of the local union. He grew up in Forsan area, just south of Big Spring. His father died suddenly in February 1966 from a self-inflicted gunshot when he was a sophomore and this had a real impact on Mackie. He had attended Forsan schools, last attending Forsan High School, dropping out before he completed his junior year.

Forsan High School-1966

He enlisted in the U.S. Marines from Big Spring on May 10, 1967. He completed boot camp at the Marine Corp Recruit Training Depot at San Diego, California and then completed ITR at Camp Pendleton, California.

He began his tour in Vietnam on October 20, 1967. He was assigned to M Company, 3rd Battalion, 9th Marines, 3rd Marine Division as a light weapon's infantryman. In late April, 1968 it became apparent that the North Vietnamese Army was again moving across the DMZ in the area north of Dong Ha. On April 29, the ARVN 2nd Infantry Regiment sent its 1st and 4th Battalions in a pincer movement to locate and engage the NVA units around An Binh. "Task Force Robbie", consisting of 1st Bn, 9th Marines reinforced with tanks from Alpha 3rd Tanks, was sent to relieve building pressure on the ARVN's southern flank.

"Robbie" ran into trouble at Cam Vu, about 5,000 meters west of An Binh, where a North Vietnamese blocking force was waiting for them. After taking 10 dead and 22 wounded in a six hour fight against a clearly superior force, "Robbie" broke off the contact and withdrew. The ARVN forces had absorbed 17 dead and 47 wounded, could not link up, and also withdrew.

At this point the 3rd Battalion, 9th Marines, was brought into the fight, advancing toward Cam Vu. India 3/9 was first to make contact, encountering an "L" shaped ambush just north of Cam Vu. As 3/9's other three companies deployed in suport of India, the NVA broke contact and withdrew under cover of artillery fire from within and north of the DMZ.

The fighting around Cam Vu was paralleled by the engagement of the 2nd Battalion, 4th Marines, with elements of the 325th NVA Division at Dai Do some 5 miles to the northeast of Cam Vu. These engagements-the 2nd ARVN Infantry, 1/9, and 3/9 at Cam Vu and 2/4 at Dai Do-were the opening engagements in what became known as the Battle of Dong Ha.

While the Cam Vu fights cost the North Vietnamese at least 197 dead, Allied losses also were high: 1st Bn, 9th Marines - 10 dead; 3rd Bn, 9th Marines - 36 dead - 1st and 4th Bns, 2nd ARVN Infantry - 17 dead. Another Permian Basin Resident, Sgt. Elmer Perry of Odessa was one of the 10 killed while serving in the lead elements of "Task Force Robbie," on April 30, 1968 during opening engagements of this battle.

Eight of the 36 dead from 3rd Bn, 3/9 were from M Company. PFC O'Brien was killed by a rocket/mortar during the battle on May 1, 1968. He sustained fragment wounds to his head and neck area. He had been in the Marines less than a year.

Trinity Memorial Gardens Cemetery, Big Spring, Texas

Mickey was buried with full military honors in Trinity Memorial Cemetery in Big Spring, Texas. He was survived by his mother Betty O'Brien of Big Spring, a sister, Patricia and a brother John K. O'Brien. He was also survived by his grandparents, Mr and Mrs. Ernest O'Brien of Big Spring and Mrs. Edna Akins of Salinas, Kansas.